network: always create dnsmasq hosts and addnhosts files, even if empty

This fixes the problem reported in:

  https://bugzilla.redhat.com/show_bug.cgi?id=868389

Previously, the dnsmasq hosts file (used for static dhcp entries, and
addnhosts file (used for additional dns host entries) were only
created/referenced on the dnsmasq commandline if there was something
to put in them at the time the network was started. Once we can update
a network definition while it's active (which is now possible with
virNetworkUpdate), this is no longer a valid strategy - if there were
0 dhcp static hosts (resulting in no reference to the hosts file on the
commandline), then one was later added, the commandline wouldn't have
linked dnsmasq up to the file, so even though we create it, dnsmasq
doesn't pay any attention.

The solution is to just always create these files and reference them
on the dnsmasq commandline (almost always, anyway). That way dnsmasq
can notice when a new entry is added at runtime (a SIGHUP is sent to
dnsmasq by virNetworkUdpate whenever a host entry is added or removed)

The exception to this is that the dhcp static hosts file isn't created
if there are no lease ranges *and* no static hosts. This is because in
this case dnsmasq won't be setup to listen for dhcp requests anyway -
in that case, if the count of dhcp hosts goes from 0 to 1, dnsmasq
will need to be restarted anyway (to get it listening on the dhcp
port). Likewise, if the dhcp hosts count goes from 1 to 0 (and there
are no dhcp ranges) we need to restart dnsmasq so that it will stop
listening on port 67. These special situations are handled in the
bridge driver's networkUpdate() by checking for ((bool)
nranges||nhosts) both before and after the update, and triggering a
dnsmasq restart if the before and after don't match.

diff --git a/src/network/bridge_driver.c b/src/network/bridge_driver.c
index fa909a1b8440d0459e53db6c1a2e16075e4bcf58..1c97f290cbf74865cef46da2ed9abc4d20e62c95 100644 (file)
--- a/src/network/bridge_driver.c
+++ b/src/network/bridge_driver.c
@@ -751,12 +751,19 @@ networkBuildDnsmasqArgv(virNetworkObjPtr network,
         if (networkBuildDnsmasqHostsfile(dctx, ipdef, network->def->dns) < 0)
             goto cleanup;
 
-        if (dctx->hostsfile->nhosts)
+        /* Even if there are currently no static hosts, if we're
+         * listening for DHCP, we should write a 0-length hosts
+         * file to allow for runtime additions.
+         */
+        if (ipdef->nranges || ipdef->nhosts)
             virCommandAddArgPair(cmd, "--dhcp-hostsfile",
                                  dctx->hostsfile->path);
-        if (dctx->addnhostsfile->nhosts)
-            virCommandAddArgPair(cmd, "--addn-hosts",
-                                 dctx->addnhostsfile->path);
+
+        /* Likewise, always create this file and put it on the commandline, to allow for
+         * for runtime additions.
+         */
+        virCommandAddArgPair(cmd, "--addn-hosts",
+                             dctx->addnhostsfile->path);
 
         if (ipdef->tftproot) {
             virCommandAddArgList(cmd, "--enable-tftp",
@@ -2882,7 +2889,10 @@ networkUpdate(virNetworkPtr net,
 {
     struct network_driver *driver = net->conn->networkPrivateData;
     virNetworkObjPtr network = NULL;
-    int isActive, ret = -1;
+    int isActive, ret = -1, ii;
+    virNetworkIpDefPtr ipdef;
+    bool oldDhcpActive = false;
+
 
     virCheckFlags(VIR_NETWORK_UPDATE_AFFECT_LIVE |
                   VIR_NETWORK_UPDATE_AFFECT_CONFIG,
@@ -2897,6 +2907,16 @@ networkUpdate(virNetworkPtr net,
         goto cleanup;
     }
 
+    /* see if we are listening for dhcp pre-modification */
+    for (ii = 0;
+         (ipdef = virNetworkDefGetIpByIndex(network->def, AF_INET, ii));
+         ii++) {
+        if (ipdef->nranges || ipdef->nhosts) {
+            oldDhcpActive = true;
+            break;
+        }
+    }
+
     /* VIR_NETWORK_UPDATE_AFFECT_CURRENT means "change LIVE if network
      * is active, else change CONFIG
     */
@@ -2938,8 +2958,30 @@ networkUpdate(virNetworkPtr net,
             if (networkRestartDhcpDaemon(network) < 0)
                 goto cleanup;
 
-        } else if (section == VIR_NETWORK_SECTION_IP_DHCP_HOST ||
-                   section == VIR_NETWORK_SECTION_DNS_HOST ||
+        } else if (section == VIR_NETWORK_SECTION_IP_DHCP_HOST) {
+            /* if we previously weren't listening for dhcp and now we
+             * are (or vice-versa) then we need to do a restart,
+             * otherwise we just need to do a refresh (redo the config
+             * files and send SIGHUP)
+             */
+            bool newDhcpActive = false;
+
+            for (ii = 0;
+                 (ipdef = virNetworkDefGetIpByIndex(network->def, AF_INET, ii));
+                 ii++) {
+                if (ipdef->nranges || ipdef->nhosts) {
+                    newDhcpActive = true;
+                    break;
+                }
+            }
+
+            if ((newDhcpActive != oldDhcpActive &&
+                networkRestartDhcpDaemon(network) < 0) ||
+                networkRefreshDhcpDaemon(network) < 0) {
+                goto cleanup;
+            }
+
+        } else if (section == VIR_NETWORK_SECTION_DNS_HOST ||
                    section == VIR_NETWORK_SECTION_DNS_TXT ||
                    section == VIR_NETWORK_SECTION_DNS_SRV) {
             /* these sections only change things in config files, so we

diff --git a/src/util/dnsmasq.c b/src/util/dnsmasq.c
index 91bf2c564d56fe38aedb089201aa3affbca83a4d..9d1c07b4779c9732c1e95b61d10395787a253fa0 100644 (file)
--- a/src/util/dnsmasq.c
+++ b/src/util/dnsmasq.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2007-2011 Red Hat, Inc.
+ * Copyright (C) 2007-2012 Red Hat, Inc.
  * Copyright (C) 2010 Satoru SATOH <satoru.satoh@gmail.com>
  *
  * This library is free software; you can redistribute it and/or
@@ -176,8 +176,9 @@ addnhostsWrite(const char *path,
     unsigned int i, ii;
     int rc = 0;
 
-    if (nhosts == 0)
-        return rc;
+    /* even if there are 0 hosts, create a 0 length file, to allow
+     * for runtime addition.
+     */
 
     if (virAsprintf(&tmp, "%s.new", path) < 0)
         return -ENOMEM;
@@ -364,8 +365,9 @@ hostsfileWrite(const char *path,
     unsigned int i;
     int rc = 0;
 
-    if (nhosts == 0)
-        return rc;
+    /* even if there are 0 hosts, create a 0 length file, to allow
+     * for runtime addition.
+     */
 
     if (virAsprintf(&tmp, "%s.new", path) < 0)
         return -ENOMEM;

diff --git a/tests/networkxml2argvdata/isolated-network.argv b/tests/networkxml2argvdata/isolated-network.argv
index 048c72b28709ba0c9dee6455678922df6e3d0c03..13e77b26a0fbf02ffb47c9fb423ada91decb46ea 100644 (file)
--- a/tests/networkxml2argvdata/isolated-network.argv
+++ b/tests/networkxml2argvdata/isolated-network.argv
@@ -4,4 +4,6 @@
 --listen-address 192.168.152.1 \
 --dhcp-range 192.168.152.2,192.168.152.254 \
 --dhcp-leasefile=/var/lib/libvirt/dnsmasq/private.leases --dhcp-lease-max=253 \
---dhcp-no-override\
+--dhcp-no-override \
+--dhcp-hostsfile=/var/lib/libvirt/dnsmasq/private.hostsfile \
+--addn-hosts=/var/lib/libvirt/dnsmasq/private.addnhosts\

diff --git a/tests/networkxml2argvdata/nat-network-dns-srv-record-minimal.argv b/tests/networkxml2argvdata/nat-network-dns-srv-record-minimal.argv
index a1e420055e93632d85f4dadc0d6e7495374f9954..210a60c01c9be2b66fa07bb991cd734dfb7f32a9 100644 (file)
--- a/tests/networkxml2argvdata/nat-network-dns-srv-record-minimal.argv
+++ b/tests/networkxml2argvdata/nat-network-dns-srv-record-minimal.argv
@@ -13,4 +13,5 @@
 --dhcp-leasefile=/var/lib/libvirt/dnsmasq/default.leases \
 --dhcp-lease-max=253 \
 --dhcp-no-override \
---dhcp-hostsfile=/var/lib/libvirt/dnsmasq/default.hostsfile\
+--dhcp-hostsfile=/var/lib/libvirt/dnsmasq/default.hostsfile \
+--addn-hosts=/var/lib/libvirt/dnsmasq/default.addnhosts\

diff --git a/tests/networkxml2argvdata/nat-network-dns-srv-record.argv b/tests/networkxml2argvdata/nat-network-dns-srv-record.argv
index 8af38c416f1c8a7107da69d9f2260fe69d4c8c99..833d3cd0f5134681b62b5dadd4269778e533372f 100644 (file)
--- a/tests/networkxml2argvdata/nat-network-dns-srv-record.argv
+++ b/tests/networkxml2argvdata/nat-network-dns-srv-record.argv
@@ -13,4 +13,5 @@
 --dhcp-leasefile=/var/lib/libvirt/dnsmasq/default.leases \
 --dhcp-lease-max=253 \
 --dhcp-no-override \
---dhcp-hostsfile=/var/lib/libvirt/dnsmasq/default.hostsfile\
+--dhcp-hostsfile=/var/lib/libvirt/dnsmasq/default.hostsfile \
+--addn-hosts=/var/lib/libvirt/dnsmasq/default.addnhosts\

diff --git a/tests/networkxml2argvdata/nat-network-dns-txt-record.argv b/tests/networkxml2argvdata/nat-network-dns-txt-record.argv
index 404b56ab49c6c40aded684e497ef4176ea7c798f..348150779116738161069d10f947aa96ef445de7 100644 (file)
--- a/tests/networkxml2argvdata/nat-network-dns-txt-record.argv
+++ b/tests/networkxml2argvdata/nat-network-dns-txt-record.argv
@@ -7,4 +7,5 @@
 --dhcp-range 192.168.122.2,192.168.122.254 \
 --dhcp-leasefile=/var/lib/libvirt/dnsmasq/default.leases \
 --dhcp-lease-max=253 --dhcp-no-override \
---dhcp-hostsfile=/var/lib/libvirt/dnsmasq/default.hostsfile\
+--dhcp-hostsfile=/var/lib/libvirt/dnsmasq/default.hostsfile \
+--addn-hosts=/var/lib/libvirt/dnsmasq/default.addnhosts\

diff --git a/tests/networkxml2argvdata/nat-network.argv b/tests/networkxml2argvdata/nat-network.argv
index 1dc8f73d16675a3acc3f169815dc116d82720b97..37fd2fca91c4ca3d298ca4212710a820661a4137 100644 (file)
--- a/tests/networkxml2argvdata/nat-network.argv
+++ b/tests/networkxml2argvdata/nat-network.argv
@@ -6,4 +6,5 @@
 --dhcp-range 192.168.122.2,192.168.122.254 \
 --dhcp-leasefile=/var/lib/libvirt/dnsmasq/default.leases \
 --dhcp-lease-max=253 --dhcp-no-override \
---dhcp-hostsfile=/var/lib/libvirt/dnsmasq/default.hostsfile\
+--dhcp-hostsfile=/var/lib/libvirt/dnsmasq/default.hostsfile \
+--addn-hosts=/var/lib/libvirt/dnsmasq/default.addnhosts\

diff --git a/tests/networkxml2argvdata/netboot-network.argv b/tests/networkxml2argvdata/netboot-network.argv
index 5a85ec2e7a2cfcce5504ae7cf1523303a38c722f..5408eb71c99d42777bc1ae0a97ed05d8cd04021c 100644 (file)
--- a/tests/networkxml2argvdata/netboot-network.argv
+++ b/tests/networkxml2argvdata/netboot-network.argv
@@ -3,5 +3,8 @@
 --except-interface lo --listen-address 192.168.122.1 \
 --dhcp-range 192.168.122.2,192.168.122.254 \
 --dhcp-leasefile=/var/lib/libvirt/dnsmasq/netboot.leases \
---dhcp-lease-max=253 --dhcp-no-override --expand-hosts --enable-tftp \
+--dhcp-lease-max=253 --dhcp-no-override --expand-hosts \
+--dhcp-hostsfile=/var/lib/libvirt/dnsmasq/netboot.hostsfile \
+--addn-hosts=/var/lib/libvirt/dnsmasq/netboot.addnhosts \
+--enable-tftp \
 --tftp-root /var/lib/tftproot --dhcp-boot pxeboot.img\

diff --git a/tests/networkxml2argvdata/netboot-proxy-network.argv b/tests/networkxml2argvdata/netboot-proxy-network.argv
index 36836b09d32cd47b5b95a8e0bc00f164d68952ba..21e01e377f7962cbb404bf22af64eb315404c2a6 100644 (file)
--- a/tests/networkxml2argvdata/netboot-proxy-network.argv
+++ b/tests/networkxml2argvdata/netboot-proxy-network.argv
@@ -4,4 +4,6 @@
 --dhcp-range 192.168.122.2,192.168.122.254 \
 --dhcp-leasefile=/var/lib/libvirt/dnsmasq/netboot.leases \
 --dhcp-lease-max=253 --dhcp-no-override --expand-hosts \
+--dhcp-hostsfile=/var/lib/libvirt/dnsmasq/netboot.hostsfile \
+--addn-hosts=/var/lib/libvirt/dnsmasq/netboot.addnhosts \
 --dhcp-boot pxeboot.img,,10.20.30.40\

diff --git a/tests/networkxml2argvdata/routed-network.argv b/tests/networkxml2argvdata/routed-network.argv
index 77e802f8434360aedc719379bf2a1483d725428c..9fedb2b4621a8ec75be8da06973e2dc703545244 100644 (file)
--- a/tests/networkxml2argvdata/routed-network.argv
+++ b/tests/networkxml2argvdata/routed-network.argv
@@ -1,3 +1,4 @@
 @DNSMASQ@ --strict-order --bind-interfaces \
 --local=// --domain-needed --conf-file= \
---except-interface lo --listen-address 192.168.122.1\
+--except-interface lo --listen-address 192.168.122.1 \
+--addn-hosts=/var/lib/libvirt/dnsmasq/local.addnhosts\